Figure 5

Influences of other glypicans on brain size regulation. (A-J) Whole-mount in situ hybridization for Gpc2, Gpc3, Gpc4, Gpc5 and Gpc6 in E9.5 wild-type (A-E) and Gpc1^-/- (F-J) mouse embryos suggests that there is no significant upregulation of other glypicans in response to Gpc1 loss. (K, L) Wet weights of fresh adult brains from allelic combinations of Gpc1^- with Gpc2^- (K) and Gpc1^- with Gpc4^lacZ (L). Genotypes are as indicated. The insertion site of the Gpc4^LacZ gene-trap allele has not been mapped, precluding development of an allele-specific PCR reaction to distinguish Gpc4^LacZ/+ from Gpc4^LacZ/LacZ animals. However, since Gpc4 is located on the X chromosome, males with a single LacZ allele are unambiguously hemizygous. Thus, the comparison in (L) is between wild-type (both sexes) and LacZ+ males. Note that Gpc2^-/- brains are not significantly different in size from wild type, nor does loss of Gpc2 enhance the phenotype of the Gpc1^-/- mouse. In contrast, the Gpc4^LacZ mutation significantly enhances the Gpc1^-/- phenotype (* and **P < 0.005). N = 7 for Gpc1^+/+;Gpc2^+/+, N = 5 for Gpc1^+/+;Gpc2^-/-, N = 3 for Gpc1^-/-;Gpc2^+/+, N = 3 for Gpc1^-/-;Gpc2^-/-, N = 2 for Gpc1^+/+;Gpc4^+/+ and N = 4 for Gpc1^+/+;Gpc4^+/Y, N = 3 for Gpc1^-/-;Gpc4^+/+ and N = 8 for Gpc1^-/-;Gpc4^+/Y, N = 14 for Gpc1^+/+;Gpc4^Lacz/Y, N = 9 for Gpc1^-/-;Gpc4^LacZ/Y.